Abstract In this theoretical study, a recently proposed segregation model is applied to segregation data of an exemplary Σ5 grain boundary (GB), which is investigated using a copper–nickel embedded-atom method potential. Segregation in the semi-grandcanonical ensemble is systematically studied by varying the chemical potential in order to explore the full composition range for temperatures from 500 K to 1000 K. As a major thermodynamic feature, the mentioned segregation model avoids the usage of interface compositions, for which an arbitrary volume must be defined, but rather models the thermodynamically unambiguous solute excess. It was shown that the solute excess and the interface formation energy could be described very accurately over a wide range of temperatures and over the entire composition range based on a composition-dependent, but temperature-independent effective energy of segregation. However, the model was initially derived for systems without lattice mismatch so that interface tensions were neglected. Since the copper–nickel system exhibits a moderate lattice mismatch of roughly 2.7%, the copper–nickel system is chosen in this study to further extend the segregation model by a linear-elastic theory to also account for the interface tensions. Using this extended model, it will be shown that the solute excess, GB tensions, and GB formation energies can be derived from the effective energy of segregation for all temperatures and over the whole composition range. As in principle only one single segregation isotherm is sufficient to determine the effective energy of segregation and derived thermodynamic interface quantities, the application of this model is especially interesting for experimental evaluations.

中文翻译：

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铜镍体系晶界偏析、张力和形成能的解析描述

摘要 在这项理论研究中，最近提出的偏析模型应用于示例性 Σ5 晶界 (GB) 的偏析数据，该模型使用铜镍嵌入原子法势进行研究。通过改变化学势来系统地研究半正则系综中的偏析，以探索 500 K 到 1000 K 温度的完整成分范围。作为主要的热力学特征，上述偏析模型避免使用界面成分，例如必须定义任意体积，而是模拟热力学上明确的溶质过量。结果表明，基于组成相关的，可以在很宽的温度范围内和整个组成范围内非常准确地描述溶质过量和界面形成能，但与温度无关的有效离析能。然而，该模型最初是为没有晶格失配的系统推导出来的，因此忽略了界面张力。由于铜-镍系统表现出大约 2.7% 的中等晶格失配，本研究中选择铜-镍系统以通过线弹性理论进一步扩展偏析模型，以考虑界面张力。使用此扩展模型，将显示溶质过量、GB 张力和 GB 形成能可以从所有温度和整个组成范围内的有效离析能量导出。因为原则上只有一个单一的偏析等温线就足以确定有效的偏析能量和导出的热力学界面量，